US3700855A - Magnetic disc assembly - Google Patents

Magnetic disc assembly Download PDF

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Publication number
US3700855A
US3700855A US100242A US3700855DA US3700855A US 3700855 A US3700855 A US 3700855A US 100242 A US100242 A US 100242A US 3700855D A US3700855D A US 3700855DA US 3700855 A US3700855 A US 3700855A
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US
United States
Prior art keywords
compartment
disc
shroud
temperature
ambient air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US100242A
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English (en)
Inventor
Clifford J Helms
Norman Mcmillan
Stelios B Papadopoulos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sperry Corp
Original Assignee
Sperry Rand Corp
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Filing date
Publication date
Application filed by Sperry Rand Corp filed Critical Sperry Rand Corp
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Publication of US3700855A publication Critical patent/US3700855A/en
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
    • G11B23/02—Containers; Storing means both adapted to cooperate with the recording or reproducing means
    • G11B23/021—Containers; Storing means both adapted to cooperate with the recording or reproducing means comprising means for reducing influence of physical parameters, e.g. temperature change, moisture

Definitions

  • ABSTRACT A magnetic disc assembly including a system for efficiently maintaining-the temperature in the disc compartment at a prescribed operating level.
  • Disc compartment temperature is maintained at a prescribed level elevated above ambient by the combined effect of moving ambient air around a cylindrical convoluted shroud surrounding the disc compartment for cooling and by selectively activating elements within the compartment for heating.
  • the shroud is surrounded by a concentric cylindrical cover and the ambient air flows between the shroud and the cover.
  • the heater elements serve to quickly bring the disc compartment temperature up to the elevated operating level and to add heat as required to maintain that level.
  • the heater elements are incorporated in the compartment within the shroud convolutions and are activated in response to a temperature sensor within the compartment.
  • An ambient air temperature sensor controls the ambient air flow.
  • a disc stack assembly supported in the disc compartment includes a plurality of discs mounted on a common shaft secured to a rotatable hub. ln operation, the discs spin very rapidly causing the air within the compartment to move in the same direction as the disc surfaces.
  • a flared baffle mounted within the compartment interrupts the moving air and creates a pressure differential between the upstream and downstream sides of the baffle. This pressure differential is employed to circulate the air within the compartment through a filter.
  • Magnetic disc assemblies are widely employed in data processing systems for mass storage. Such assemblies usually consist of a plurality of rotatable discs, each having a pair of magnetic surfaces. Some such systems use a fixed head arrangement wherein a plurality of heads are provided for each disc surface, each head being dedicated to a different disc track.'Other systems use a movable head arrangement wherein a small number of heads, e.g., four, are carried by an arm adjacent each disc surface with the arm being mounted for linear movement along a disc radius to thus enable a head to be moved into position adjacent any selected one of a plurality of tracks.
  • the tracks on the disc surface must be spaced very closely, e.g., 150 tracks per inch, requiring, of course, that a very precise linear positioner be provided for positioning the heads.
  • a very precise linear positioner it is essential that the operating temperature in the disc compartment be maintained substantially constant to minimize disc dimension variations. That is, if the operating temperature in the disc compartment were permitted to vary significantly, the disc dimensions would also exhibit a significant variation, and thus cause an error in positioning accuracy. If this occurs, it would not be possible to accurately position a head for reading a track at one temperature which was written at adifferent temperature regardless of the precision of the linear positioner. Unless precautions are taken, temperature variations are likely to occur within the disc compartment as a consequence of the heat produced by the friction between the spinning disc surfaces and the air within the disc compartment.
  • a system for maintaining the temperature in a disc compartment at a certain operating level by permitting the compartment temperature to rise to an elevated level whereat it is maintained by the combined effect of ambient air flow and heater element actuation;
  • the disc compartment is enclosed by a cylindrical shroud formed of aluminum convoluted to yield a surface length greater than its axial length to optimize heat transfer to ambient air flowing therepast.
  • the shroud is surrounded by a cylindrical cover and the ambient air flows between the shroud and the cover. The amount of air flow is preferably controlled in response to ambient air temperature.
  • heater elements are mounted in the disc compartment within the shroud convolutions.
  • the heater elements serve both to accelerate the rise of the compartment temperature to the elevated operating level and to maintain the temperature at that level.
  • the duration of actuation of the heater element is preferably controlled in response to compartment air temperature.
  • a flared baffle is provided within the disc compartment to create a pressure differential for circulating the air within the compartment through a filter.
  • FIG. 1 is a perspective view of a magnetic disc assembly in accordance with the present invention
  • FIG. 2 is a vertical sectional view taken substantially along the plane 2-2 of F IG. 1;
  • FIG. 3 is a vertical sectional view taken substantially along the plane 3-3 of FIG. 2, illustrating ambient air flow around the convoluted shroud;
  • FIG. 3A is an enlarged sectional view through the heater element of FIG. 3;
  • FIG. 4 is a sectional view illustrating the disc compartment and plate carrying the flared baffle.
  • FIG. 5 is a top view of the end plate illustrated in FIG. 4.
  • FIG. 1 illustrates a magnetic disc assembly embodying the teachings of the present invention.
  • magnetic disc assemblies are widely employed in data processing systems for mass storage. Such assemblies usually consist of a plurality of rotatable discs each having a pair of magnetic surfaces upon which information can be recorded.
  • Many magnetic disc assemblies employ a movable head arrangement for reading and writing information.
  • a relatively small number of heads are supported on an arm adjacent each disc surface with the arm being mounted for linear movement along a disc radius. In this manner, a head can be moved into any selected one of a plurality of positions along the disc radius to record concentric tracks of information on the disc surface.
  • the resolution with which the heads can be repeatably positioned determines the track density which, of course, constitutes a significant factor in the determination of the disc storage capacity.
  • the assembly 10 of FIG. 1 is comprised of a housing 12 enclosing both mechanical and electronic subassemblies.
  • the mechanical subassembly is essentially comprised of a stack of discs 14 including a plurality of individual discs 16 all perpendicularly mounted on a central shaft 18.
  • the shaft 18 is mounted for rotation about its longitudinal axis and is rotatably driven, as by a belt train (not shown), by a drive motor 20.
  • the disc stack 14 is supported within a disc compartment 21 defined within a substantially cylindrical shroud 22.
  • the shroud 22 is formed of a wall of substantially uniform thickness and of a material having good heat conductivity characteristics, e.g. aluminum.
  • the shroud wall 24 is convoluted along the length thereof as is best illustrated in FIG. 2. The convolutions are provided in order to increase the wall surface area exposed to the disc compartment 21 in order to maximize heat transfer from the disc compartment to the wall.
  • the shroud comprises a substantially enclosed cylinder open only in the area 26 for enabling the head carrying arms to project into the disc compartment 21.
  • a substantially cylindrical cover 28 is mounted around the shroud 22.
  • the inner surface of the cover wall 30 is spaced from the outer surface of the shroud wall 24 to define a passageway 32 therebetween.
  • the cover 28 opens in the region 34 shown in FIG. 3 into an air supply conduit 36.
  • Air supplied to the conduit 36 can be drawn through an upper portion 38 of the passageway 32 or a lower passageway portion 40. Air drawn through the upper passageway portion 38 is exhausted at port 42 defined in the cover while air drawn through passageway portion 40 is exhausted through port 44.
  • Ports 42 and 44 are respectively coupled to air conduits 46 and 48 (FIG. 1) leading to the electronic subassemblies contained within blocks 50 shown in FIG. I.
  • a movable flap 4 is mounted within the air conduit 36 to selectively permit air flowing through the conduit 36 to be directed to both upper and lower passageway portions 38 and 40 or to passageway portions 38 only.
  • arcuately shaped heater elements 60 are mounted within at least some of the convolutions in shroud 22 as is best shown in FIGS. 2 and 3.
  • the heater elements are preferably comprised of a housing 62 formed of aluminum tubing bent into an arcuate shape to conform to the radius of curvature of the shroud.
  • a continuous length of heater element wire 66 is mounted in the shroud and electrically insulated from the aluminum tubing by insulative tubing 68.
  • Insulative tubing 71 positions the heater element wire within the heater element housings 62.
  • the discs be dimensionally stable and accordingly, it is necessary that the temperature within the disc compartment 21 be maintained at a substantially constant level. This operating temperature level must be maintained despite the fact that an enormous amount of heat is generated during operation as a consequence of the friction between the rapidly rotating disc surfaces and the air within the disc compartment.
  • ll 24 inch diameter discs are mounted within the disc compartment and are rotated at 1,800 rpm. The friction generated between the disc surfaces and the disc compartment air acts as a 1,000 watt heater.
  • an operating temperature level within the disc compartment is selected which is elevated from ambient. More particularly, for a typical disc assembly intended to operate over an ambient temperature range of 60 F. to 90 R, an operating temperature level within the disc compartment of 1 16 F. 1 1 may be selected.
  • ambient air is supplied through the air conduit 36 to either the upper passageway portion 38 or both the upper and lower passageway portions 38 and 40.
  • ambient air when the ambient air is directed to both the upper and lower passageways, it will be assumed to be flowing through the conduit 36 at 300 cubic feet per minute (CFM).
  • CFM cubic feet per minute
  • the ambient air When the ambient air is supplied only through the upper passageway portion, it will be assumed to flow at 150 CFM.
  • the 1,000 watts generated within the disc compartment as a consequence of friction may, for example, produce a 20 F. rise therein above the temperature of the ambient air.
  • the heat required to be supplied to the disc compartment by the heater elements 60 will not be nearly as great.
  • Actuation of the heater elements 60 is controlled by a temperature sensor mounted within the disc compartment. Whenever the disc compartment temperature falls below the operating level of 1 16, this fact is communicated to the control means 72 to energize the heater element 60. In order to prevent hunting, the heater elements are energized for limited duration intervals.
  • the heater elements 60 are not only useful to maintain the disc compartment temperature at the elevated operating level but in addition are important to enable the disc compartment temperature to rapidly reach that level when the assembly is first turned on. That is, utilization of the heater elements 60 in accordance with the invention can reduce the time required to stabilize the disc compartment temperature at the elevated operating level to less than 30 minutes, for example.
  • the flap 54 within the air conduit 36 is provided to reduce the requirements on the heater element 60. That is, if the ambient temperature is very low, e.g. less than 75 F., then it is desirable to reduce the amount of heat carried away by the ambient air flow through the passageway 32 between the shroud 22 and cover 30.
  • a temperature sensor 80 responsive to the ambient air temperature controls the position of the flap 54 so that whenever the ambient air temperature is below 75 F., air flow is restricted to the upper passageway portion 38.
  • the disc compartment end plate 82 is provided with a pair of openings 84 and 86. Opening 86 communicates with an air conduit 88 leading to an absolute filter 90.
  • An air conduit 92 couples the output of the absolute filter to the opening 84 in the end plate 82.
  • a flared baffle 94 is mounted against the end plate.
  • the flared baffle 94 consists of a baffle member 96 whose width decreases smoothly as measured at increasing displacements from the end plate 82.
  • the baffle member 96 creates turbulence in the air movement which produces a positive differential pressure at the upstream side 98 of the baffle member as compared to the pressure at the downstream side 100.
  • This differential pressure between the sides 98 and 100 of the baffle member 96 forces air through the end plate opening 86 and conduit 88 into the absolute filter 90 from which it is returned through the end plate opening 84 to the disc compartment.
  • the disc compartment air is filtered without requiring the use of any active filter motors but by instead relying on the disc motion itself to create the air movement for filtering.
  • an improved magnetic disc assembly has been disclosed herein in which dimensional stability-is achieved by maintaining disc compartment temperature at a constant operating level elevated from ambient.
  • the disc compartment temperature is maintained constant as a consequence of the joint effects of ambient air flow and heater element actuation.
  • disc compartment air is filtered as a consequence of the disc motion which produces air movement through a filter.
  • a magnetic disc storage assembly including:
  • a cover surrounding said shroud and spaced therefrom so as to provide a passageway between the shroud and the cover;
  • means including an air intake conduit for drawing ambient air through said passageway and over the outer surface of said shroud to thereby remove the heat from said compartment;
  • first temperature sensing means in said compartment for indicating when the temperature therein is below a prescribed operating level
  • the storage assembly of claim 2 including a plurality of electronic circuit modules
  • conduit means coupled between at least one of said exhaust openings and said electronic circuit modules for exhausting air from said passageway adjacent to said circuit modules for cooling.
  • said shroud is comprised of a wall formed of good heat conductive material and having a plurality of convolutions formed therein.
  • each of said convolutions extends around the circumference of said cylindrical shroud; and wherein said heater means is comprised of at least one arcuate heater element supported in one of said convolutions.
  • the storage assembly of claim 1 including:
  • a magnetic disc storage assembly which includes:
  • baffle member is flared and has a width which decreases smoothly measured at increasing displacements from 10 said plate.

Landscapes

  • Cooling Or The Like Of Electrical Apparatus (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Rotational Drive Of Disk (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Control Of Vending Devices And Auxiliary Devices For Vending Devices (AREA)
US100242A 1970-12-21 1970-12-21 Magnetic disc assembly Expired - Lifetime US3700855A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US10024270A 1970-12-21 1970-12-21

Publications (1)

Publication Number Publication Date
US3700855A true US3700855A (en) 1972-10-24

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US100242A Expired - Lifetime US3700855A (en) 1970-12-21 1970-12-21 Magnetic disc assembly

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US (1) US3700855A (it)
JP (1) JPS5413765B1 (it)
CA (1) CA953817A (it)
DE (1) DE2163574C3 (it)
FR (1) FR2119557A5 (it)
GB (1) GB1379396A (it)
IT (1) IT944136B (it)
NL (1) NL7116433A (it)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3876860A (en) * 1973-03-23 1975-04-08 Matsushita Electric Ind Co Ltd Tape heater
EP0020933A1 (en) * 1979-06-29 1981-01-07 International Business Machines Corporation Control of relative humidity in disk files
US6922308B1 (en) * 2000-09-29 2005-07-26 Western Digital Technologies, Inc. Disk drive comprising a cover shaped to improve radial and axial shrouding

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE794003A (fr) * 1972-01-13 1973-05-02 Memorex Corp Systeme pour regir une circulation d'air
JPS54137309A (en) * 1978-04-18 1979-10-25 Mitsubishi Electric Corp Magnetic disk memory
US4285018A (en) * 1979-01-25 1981-08-18 International Business Machines Corporation Disk file
US4642715A (en) * 1984-11-01 1987-02-10 Miltope Corporation Environmental conditioning and safety system for disk-type mass memories

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2721729A (en) * 1953-03-16 1955-10-25 Jurian W Van Riper Temperature control mechanism for extrusion apparatus
US2893055A (en) * 1956-08-06 1959-07-07 Farrel Birmingham Co Inc Apparatus for heating plastic material in an extruding machine
US2912556A (en) * 1958-05-02 1959-11-10 Farrel Birmingham Co Inc Electrically heated roll for calenders or the like
GB910109A (en) * 1959-01-30 1962-11-07 Gen Electric Co Ltd Improvements in or relating to electric thermal storage space heaters
GB1017665A (en) * 1962-04-19 1966-01-19 John Henry Ellinger Improvements in or relating to heating systems utilizing a heat storage medium
US3525452A (en) * 1967-03-31 1970-08-25 Linde Ag Method and device for thermally insulating a vessel

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2721729A (en) * 1953-03-16 1955-10-25 Jurian W Van Riper Temperature control mechanism for extrusion apparatus
US2893055A (en) * 1956-08-06 1959-07-07 Farrel Birmingham Co Inc Apparatus for heating plastic material in an extruding machine
US2912556A (en) * 1958-05-02 1959-11-10 Farrel Birmingham Co Inc Electrically heated roll for calenders or the like
GB910109A (en) * 1959-01-30 1962-11-07 Gen Electric Co Ltd Improvements in or relating to electric thermal storage space heaters
GB1017665A (en) * 1962-04-19 1966-01-19 John Henry Ellinger Improvements in or relating to heating systems utilizing a heat storage medium
US3525452A (en) * 1967-03-31 1970-08-25 Linde Ag Method and device for thermally insulating a vessel

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3876860A (en) * 1973-03-23 1975-04-08 Matsushita Electric Ind Co Ltd Tape heater
EP0020933A1 (en) * 1979-06-29 1981-01-07 International Business Machines Corporation Control of relative humidity in disk files
US6922308B1 (en) * 2000-09-29 2005-07-26 Western Digital Technologies, Inc. Disk drive comprising a cover shaped to improve radial and axial shrouding

Also Published As

Publication number Publication date
DE2163574A1 (de) 1972-07-06
DE2163574B2 (de) 1973-05-17
JPS5413765B1 (it) 1979-06-02
GB1379396A (en) 1975-01-02
FR2119557A5 (it) 1972-08-04
IT944136B (it) 1973-04-20
CA953817A (en) 1974-08-27
NL7116433A (it) 1972-06-23
DE2163574C3 (de) 1973-12-20

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